All Questions

1
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0answers
49 views

When will Hund's rules fail?

I heard someone mentioned that Hund's rules do not always work. Looking at atomic spectrum: (https://qudev.phys.ethz.ch/phys4/PHYS4_lecture10v1_2page.pdf page 10 Hg spectrum) How could singlet (with ...
0
votes
1answer
32 views

How to calculate electrostatic potential at a point w.r.t an ensemble of point charges?

Given an ensemble of charges, how to derive the electrostatic potential at any point due to the ensemble? For example, consider six point charges, each approaching the origin along the three co-...
0
votes
2answers
50 views

Differential equations for the LC circuit

On wikipedia one can find that the DE for an LC circuit is given by $$\ddot I+\frac{1}{LC}I=0$$In one of my papers however I found the equation $$\ddot Q+\frac{1}{LC}Q=0$$ and I've been confused by ...
1
vote
1answer
56 views

An intuitive explanation of the basis-independency of EPR pair

As usual, we write the EPR pair as $$ \frac{1}{\sqrt2}(\left|00\right> + \left|11\right>). $$ A property of the EPR pair is that this definition is basis-independent, which means $$ \frac{1}{\...
1
vote
0answers
21 views

Derive the virial theorem from hydrostatic equikibrium

Consider the equation of hydrostatic equilibirium as follows as applied to a stellar object: $$ \frac{dP}{dr } = \frac{-GM\rho}{r^2} $$ I know it is intimately related to the virial theorem but I ...
2
votes
0answers
70 views

What orbit does a planet have to have to be a planet? [on hold]

Other questions have dealt with where you could find a planet-like object, and what a planet has to consist of to count as a planet. But this question is directed as what orbit or path an object would ...
0
votes
1answer
34 views

Fringe pattern in Michelson interferometer

It's given that CA - CB is d, the angle CAE is $\theta$. (E is not on the normal of mirror M1). I want to find the condition for maxima at E (as a function of $\theta$). I tried finding the path ...
0
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0answers
34 views

Can someone help me get the S&M package for my thesis on spinor helicity amplitude formalism? [on hold]

So my thesis director told me to download a package for Mathematica called S&M (Spin and Mathematica) and i couldn't find it when i googled it.
1
vote
1answer
47 views

$sp^3$ Hybridization wavefunctions and probability density

I have plotted a hydrogen-like sp3-hybrid orbital probability density and it looks like this: I can plot 4 overlapping probability densities in a tetrahedral shape: So far it looks OK. But when I'm ...
-2
votes
1answer
31 views

Time difference between all particles and waves

Since all particles and waves were created simultaneously in the big-bang would there be any time difference between any interacting particles and/or waves?
-4
votes
0answers
26 views

Has anyone measured more than just one polarisation on each side in a quantum entanglement experiment?

I've been looking at the literature about quantum entanglement. More specifically, I am referring to experiments such as this https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.49.1804 that ...
-1
votes
0answers
40 views

Confused with formula used for graph [on hold]

Can anyone explain to me how you get both the distance and velocity to zero using the following formula? I keep getting a different answer than that of the graph below. By the way, the object is ...
0
votes
0answers
10 views

spinless and time reversal symmetry breaking of p-wave pairing in topological superconductors

In the context of Majorana zero modes, I often hear that the p-wave pairing is effectively 'spinless' and time reversal symmetry broken. I understand that s-wave and p-wave refer to the spin portion ...
0
votes
0answers
29 views

Wilson loop and Polyakov loop

As I understand, the Wilson line is the operator $W(x) = P\exp(i\int_{xi}^{xf} A.dx)$, where $P$ is path ordering. The Polyakov loop $P(x)$ on the other hand is the trace of the Wilson loop $W(x)$ ...
-4
votes
0answers
23 views

Vertical oscillation [on hold]

In the figure, A mass of m=1kg is held with two springs of force constant k=50N/m.When the mass is suspended, it makes an angle,θ=30degree. What's the angular frequency of vertical oscillation?
-2
votes
0answers
30 views

Work done against electric field [on hold]

If a charged body has $10^{-4}$ C charge and radius of $1 m$ then find the amount of work done against the elctric field in contracting the body for $0.5$ m radius. I am fed up with the question.I am ...
0
votes
0answers
25 views

Gravitational lensing, indices of refraction and the size of the universe

Been pondering the following question for over 15 years now. Is it possible that the size of the universe has been over estimated due to the effects of gravitational lensing and boundary indices of ...
1
vote
0answers
32 views

How is Inönü-wigner contraction done?

I have read that little group for the massive particles is $SO(3)$ and for the massless particles is $E(2)$ in 4 dimensions. How does one take zero mass limits for the representations and show that it ...
0
votes
0answers
19 views

Hölder exponent and its relation to multifractality

Suppose that for a function $f(x)$, I have discrete set of numbers for $x$ with size $N$ (and the corresponding values for $f(x)$). They show multi-fractality properties: $P_q = \sum_{x=1}^N f(x)^{2q}...
1
vote
0answers
21 views

Book recommendations : Classical Mechanics [duplicate]

I know this question has been asked so many times on this website but neither do the questions nor the answers satisfy my requirements accordingly. I'm yet to go to a university with a keen interest ...
-6
votes
0answers
64 views

How to understand kinetic energy intuitively in moving object in sense of mass and velocity squared [on hold]

Momentum = p(vector) = m x V I can understand momentum as quantity of motion , inertial mass in motion, strength of non-accelerated moving object. Is there any way similar to understand kinetic ...
0
votes
1answer
54 views

What's the difference between a generating function and a generator?

Usually in physics we use the notion generator to describe the infinitesimal elements associated with any finite Lie group transformation. But in the context of the Hamiltonian formalism, all authors ...
0
votes
1answer
54 views

Are symmetries necessarily canonical transformations?

A canonical transformation is defined as a transformation such that afterwards Hamilton's equations still hold. It can then be shown that this requirement implies that canonical transformations are ...
-3
votes
1answer
32 views

Which direction the currect will flow?

I know if there is no R3 and R4, the R2 will be short circuited (Current most likely flow through the circuit that has smaller resistance). My confusion is, if the R3 and R4 are there, should we short ...
-2
votes
0answers
15 views

any information about Magnetoresistance please? [on hold]

i need any imformation or explaination or some resources too magnetoresistance please i didn't find nothing in google . any help please thank you
0
votes
1answer
39 views

Vacuum polarization contribution to magnetic moment

Where I can find the calculation of muonic (or electronic, it does not matter) vacuum polarization contribution to the anomalous electron magnetic moment? I mean the diagram (c):
1
vote
3answers
77 views

How can we derive from $\{G,H\}=0$ that $G$ generates a transformations which leaves the form of Hamilton's equations unchanged?

In the Hamiltonian formalism, a symmetry is defined as transformation generated by a function $G$ is a symmetry if $$\{G,H\}=0 ,$$ where $H$ denotes the Hamiltonian. On the other hand, a symmetry is ...
-4
votes
0answers
18 views

A balloon is descending with 10m/s. When it is at 100m from the ground, a stone is thrown. Calculate the velocity of the stone at 20sec [on hold]

Assumed initial velocity of the stone to be 10m/s and found that it would cover 100m in about 3.585 seconds. But, the question is asking its velocity at 20sec.
1
vote
0answers
21 views

Geant 4, simulate Tc-99m decay

I have a setup of Monte Carlo simulations in Geant4, and I'm able to simulate radioactive events from isotopes such as I-131 and F-18, which are defined in the RadioactiveDecayData5.2 files. Tc-99m ...
-2
votes
0answers
15 views

It is about Electrostatic Problem in electric field,flux [on hold]

Two point charges 16nC and 8nC are situated at the corners B and C of an equilateral triangle of side 0.03m. Find the magnitude and direction of the resultant electric field at the vertex A of the ...
-1
votes
0answers
37 views

Assuming standard pressure and temperature, how far would a given air molecule move in 1 hour

I'm trying to calculate how far a given Air Molecule would actually traverse in a room in 1 hour assuming standard states (i.e. thermal equilibrium and approximately standard temperature and pressure.)...
0
votes
0answers
32 views

Time units in simulation

I am hoping that someone could give me some insight about my problem. Currently I want to simulate the evolution of a gaussian wavepacket in a time-dependent potential using the Crank-Nicolson scheme. ...
0
votes
1answer
24 views

Bond graph, how to use it? [on hold]

Yesterday I heard the word "bond graph" and I felt like searching a bit about it. From what I understood, it is a graph that links the flow of energy between "states" in multiphysics systems. I am ...
0
votes
0answers
8 views

What are the differences between a Michelson and Self-Mixing interferometer?

I'm approaching to interferometric devices. I would say that Michelson interferometer uses a laser source and a "discrete" system of mirrors and other optical components such lenses and screens. On ...
1
vote
0answers
20 views

Wave-like properties of particles [duplicate]

If we consider a particle such as an electron to have wave-like properties too, what kind of wave it is? What is exactly meant by its wavelength?
-2
votes
2answers
41 views

Does pressure decreases in accelerating fluids?

Bernuolli says that in a pipe when speed increases pressure also decreases and that happen when pipe become narrower. So,if a fluid accelerate (increases speed) due to ...
5
votes
1answer
327 views

General derivative of the exponential operator w.r.t. a parameter

I am interested in the calculation of the general $N$th derivative w.r.t. a parameter $\lambda$ of a quantum mechanical exponential operator with the following structure: \begin{equation*} \frac{\...
-1
votes
1answer
24 views

What is the different of imaging using Ultrasound and Terahertz radiation [on hold]

Right now, I am developing an ultrasound NDT system for crack detection in railway track. Then, I read about terahertz imaging, I am really curious what is the different between terahertz imaging and ...
2
votes
1answer
47 views

Electromagnetic field tensor and antisymmetry

Why does the inner product between the four force (caused by the electromagnetic field tensor) and the four velocity equaling zero imply that the electromagnetic field tensor is antisymmetric? This ...
-1
votes
0answers
18 views

what's the main difference between electrostaic potential,potential difference and electrostatic potential energy? [duplicate]

Please make it possible to grasp in layman terms,in terms of everyday life with good examples.
2
votes
0answers
22 views

Understanding the variational / functional derivative (in relation to the Euler-Poincaré equation)

I'm trying to understand the Euler-Poincare equations, which reduce the Euler-Lagrange equations for certain Lagrangians on a Lie group. I'm reading Darryl Holm's "Geometric mechanics and symmetry", ...
-1
votes
1answer
39 views

Distance between the luope and the virtual picture: I can not see any

I have a biconvex lens. f=45mm. (This is a loupe). I have an object (G). This object is G=64mm broad. When I place this object in a distance of g=42mm in front of the lens I get a virtual picture. I ...
0
votes
1answer
13 views

Convert negative parameters of Altitude Height into possitive using BMP180 Sensor

I am using BMP180 I2C sensor interface with Arduino and with the help of mentioned below code ...
-1
votes
0answers
42 views

NPN transistors voltage drop between base and collector

Well I understand why if we increase the voltage between the emmiter and the collector the base current is reduced (it is reduced because the reverse bias depletion region width is increased so less ...
0
votes
0answers
17 views

Is it possible for electromagnetic waves in the Extreme Low Frequency range to carry HQ video and audio signals? [duplicate]

I had just finished this interesting read on a us navy project and was wondering how Brain computer interfaces are touting in the near future to pick up thoughts that might need the same bit rates as ...
-1
votes
0answers
19 views

Electric field on dipole with different directions [on hold]

Griffith's E&M problem 4.5 page 165 In the figure p1 and p2 are perfect dipoles a disantce r apart. What is the torque on p1 due to p2.? Wjat is the torque on p2 due to p1? well i calculated ...
2
votes
1answer
43 views

Resistor Capacitor circuits

I am a high school physics teacher and came across some issues today that I am unable to explain. We made a circuit with an $11$ V power source connected to a $100~k\Omega$ resistor and $100~\mu F$ ...
0
votes
0answers
12 views

how spinfull chains in 1d are possible since spin is not well defined in 1d?

as far as I know, in QM spin is not defined in 1d, because of algebra$\mathfrak{su}(2)$ can not be satisfied in 1d. however we talk about spin chains, spinfull luttinger liquids in 1d all the time. I ...
0
votes
0answers
18 views

How do we quantify and measure the net entropy of today's universe?

We know that the Universe evolved from a very low entropy state in the early universe to very high entropy state of today's universe. What is the quantitative definition of the net entropy of the ...
47
votes
2answers
7k views

Why didn't Lorentz conclude that no object can go faster than light?

Based on Lorentz factor $\gamma = \frac{1}{\sqrt {1-\frac{v^2}{c^2}}}$ it is easy to see $v < c$ since otherwise $\gamma$ would be either undefined or a complex number, which is non-physical. Also, ...

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